The present invention relates to condition indicating systems and more particularly to alarm indicating systems which may be of the fire and/or security type.
Prior art condition indicating circuits are energized typically in one of two ways. The first way is to supply the sensing apparatus with continuous power. However, as can be readily seen, the application of continuous power to an alarm apparatus results in the undue use of power as compared to circuits which energize the sensing apparatus by the use of pulses of energy.
The prior art has recognized that, if the sensing apparatus receives energy pulses rather than a continuous energy supply, power will be saved. Therefore, the prior art devised this second way of energizing the alarm apparatus; i.e. supplying pulses of energy to condition indicating circuits. However, these prior art systems require the use of an intergrating capacitor which is maintained in either a charged condition or a discharged condition as long as a receiver receives pulses of energy. If the pulses supplied to the receiver cease or if the receiver receives continuous energization, the capacitor discharges or charges to provide an alarm or indication. This prior art apparatus requires the use of an integrator and is unsuitable if more than one sensor is to be supplied from a single power supply.